<template>
    <div>
        <router-link 
            tag="div" 
            to="/" 
            class="header-abs"
            v-show="showAbs">
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div 
            class="header-fixed" 
            v-show="!showAbs"
            :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>

<script>

export default {
    name: 'DetailHeader',
    data() {
        return {
            showAbs: true,
            opacityStyle: {
                opacity: 0
            } 
        }
    },
    methods: {
        handleScroll () {
            const top = document.documentElement.scrollTop
            if (top > 60) {
                let opacity = top / 140
                opacity = opacity > 1 ? 1 : opacity
                this.opacityStyle = { opacity }
                this.showAbs = false
            }else {
                this.showAbs = true
            } 
            
        }
    },
    activated () {
        window.addEventListener('scroll', this.handleScroll)
    },
    deactivated () {
        window.removeEventListener('scroll', this.handleScroll)
    }
    
}
</script>

<style lang="stylus" scoped>
@import '~styles/variables.styl'

    .header-abs
        position absolute
        top .2rem
        left .2rem
        width .8rem
        height .8rem
        line-height .8rem
        border-radius .4rem
        text-align center
        background rgba(0, 0, 0, .4rem)
        .header-abs-back
            font-size .4rem
            color #fff
    .header-fixed
        position fixed
        left 0
        right 0
        top 0
        z-index 2
        height $headerHeight
        line-height $headerHeight
        text-align center
        color #fff
        background $bgColor
        font-size .32rem
        .header-fixed-back
            position absolute
            top 0
            left 0
            width .64rem
            text-align center
            font-size .4rem
            color #fff
</style>